The medical community is continually engaged in efforts to enhance the effective delivery of drugs across the skin. Many of the concerns associated with oral administration can often be avoided by topically administering an active agent to a subject in need thereof. For example, reliable delivery of a pharmaceutically active agent to organs or tissues in need thereof via oral administration is often difficult due to variable rates of absorption and metabolism associated with oral delivery. In contrast, topical administration of a pharmaceutically active agent can provide high doses of the active agent directly to the desired area, often minimizing side effects.
One such way of delivering drugs across the skin surface is by way of a non-occlusive transdermal and/or topical dosage form. Some non-limiting examples of non-occlusive transdermal and topical semi-solid dosage forms include creams, ointments, gels, foams, sprays, solutions, and lotions (i.e., emulsions, or suspensions). However, the inefficiencies of drug permeation across the skin are well known. In fact, the permeation of a drug in a non-occlusive transdermal dosage form can be as little as 1% and usually is no more than 15%. Thus, a vast majority of the active drug remains unabsorbed on the skin. Because the vast majority of the drug does not penetrate the skin surface, the bioavailability of the particular drug is not optimal, and a high risk of contamination of other individuals in close proximity to the user is presented by the unwanted transfer of the pharmaceutical formulation in the non-occlusive dosage form. Various methods have been tried to improve the percutaneous absorption of pharmacologically active substances. For example, pharmacologically active substances were modified to form prodrugs and complexes. However, administration of these agents requires detailed studies on the individual pharmacologically active substance, resulting in large monetary and time investments.
Occlusive dosage forms present some advantages over non-occlusive dosage forms, such as assisting the rate of penetration of drugs across the skin. However, occlusive dosage forms also exhibit several major drawbacks. For example, occlusive dosage forms present a high potential of local irritation caused by the prolonged contact of the drug, volatiles, vehicle excipients, and the adhesive used to attach the occlusive device, e.g., the patch, to the skin. In addition, the occlusive nature of certain dosage forms, such as the patch device, also restrict the natural ability of the skin to “breathe,” thereby increasing the risk of irritation. In addition to the aforementioned drawbacks of occlusive dosage forms, significant serious hazards have been documented regarding the high drug loading that is specific to patches.
Although attempts have been made to overcome drawbacks associated with both occlusive and non-occlusive topical drug forms, such attempts have been unsuccessful. Accordingly, there remains a need to provide a pharmaceutically acceptable topical pharmaceutical formulation system that overcomes the disadvantages of these systems.